Flush-by system

ABSTRACT

A flushing apparatus for flushing a downhole pump having a rotor and a stator includes a lifting device forming part of a wellhead assembly. The lifting device is attached to the rotor, such that when activated, the lifting device applies a lifting force to lift the rotor out of the stator. There is a fluid connection on the wellhead assembly for flushing fluid through the stator once the rotor has been removed from the stator.

FIELD

The present invention relates to a system for performing a flush-by of a pump, and a method of performing the same.

BACKGROUND

When pumps, such as downhole pumps, become sanded-in, waxed-in or otherwise clogged, a flush-by truck must be called onsite to remove the rotor from the stator and then flush diluent through the stator to clear the blockage.

SUMMARY

A flushing apparatus for flushing a downhole pump having a rotor and a stator comprises a lifting device forming part of a wellhead assembly. The lifting device is attached to the rotor, such that when activated, the lifting device applies a lifting force to lift the rotor out of the stator. There is a fluid connection on the wellhead assembly for flushing fluid through the stator once the rotor has been removed from the stator.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein:

FIG. 1 is a schematic view in partial cross-section of the flushby system.

FIG. 2 is a schematic view in partial cross-section of the flushby system with the rotor lifted from the stator.

FIG. 3 is a schematic view in partial cross-section of the flushby system with an alternative lifting device.

DETAILED DESCRIPTION

A flush-by system generally identified by reference numeral 10, will now be described with reference to FIG. 1 through 3.

Structure and Relationship of Parts

Referring to FIG. 1, a progressive cavity pump 12, such as a progressive cavity pump, having a rotor 14 and stator 16 is driven by a drive head 18 at surface. Referring to FIG. 2, when resistance against the movement of rotor 14 within stator 16 increases, such as by sand, wax, or other substances, a lifting device 20 associated with drive head 18 is used to lift rotor 14 out of stator 16. An on-site tank of fluid 22, or other convenience source of fluid, is then used to flush the stator using any suitable flushing fluid through a connection 23 on the wellhead assembly 26 that is known in the art. Tank of fluid 22 may be a tank that is currently used to keep a small flow of fluid down to pump 12, in which case, a modification must be made to allow for a greater flow of fluid from tank 22 to attain the necessary flow rate and pressure of the fluid being used to flush pump 12.

Lifting device 20 may be a multi-stage hydraulic ram 24 as shown, or other type of piston, such as mechanical or electric. Referring to FIG. 3, the mechanical means may include a gear box 28 that, when engaged, causes rotor 14 to lift out of stator 16. For size considerations, a multistage ram is preferred, however it will be understood that any suitable extendable design could be used, such as a single ram 30 as shown in FIG. 3. Lifting device 20 forms part of a wellhead assembly 26 in which it may be directly mounted to the wellhead, or indirectly through other wellhead equipment, such as drive head 18 as shown. In each of these examples, lifting device 20 rotates or allows rotor 14 to rotate in order to allow it to be removed from stator 16.

Lifting device 20 and fluid flow from tank 22 may each be controlled by a controller (not shown), which may be operated manually, automatically, locally or remotely. The operation of lifting device 20 and fluid flow from tank 22 may be initiated by: high torque, low efficiency or flow rate from the wellhead, base solids and water, a certain period of time, completion of coil tubing work, or completion of well maintenance. These indicators may be sensed using sensors or input manually into the controller, either remotely or locally.

In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.

The following claims are to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, and what can be obviously substituted. Those skilled in the art will appreciate that various adaptations and modifications of the described embodiments can be configured without departing from the scope of the claims. The illustrated embodiments have been set forth only as examples and should not be taken as limiting the invention. It is to be understood that, within the scope of the following claims, the invention may be practiced other than as specifically illustrated and described. 

1. A flushing apparatus for flushing a downhole pump having a rotor and a stator, the flushing apparatus comprising: a lifting device forming part of a wellhead assembly, the lifting device being attached to the rotor, such that when activated, the lifting device applies a lifting force to lift the rotor out of the stator; and a fluid connection on the wellhead assembly for flushing fluid through the stator once the rotor has been removed from the stator.
 2. The flushing apparatus of claim 1, wherein the lifting device and the source of fluid are controlled by a controller.
 3. The flushing apparatus of claim 2, wherein the controller is activated manually.
 4. The flushing apparatus of claim 2, wherein the controller is activated in response to an input signal, the input signal being generated by a condition of high torque, low efficiency, low flow rate, base solids and water, time, completion of coil tubing work, or completion of well maintenance.
 5. The flushing apparatus of claim 2, wherein the controller receives input signals locally or by a remote input.
 6. The flushing apparatus of claim 1, wherein the lifting device is a telescopic ram.
 7. The flushing apparatus of claim 1, wherein the lifting device is hydraulically driven.
 8. The flushing apparatus of claim I, wherein the lifting device is gear driven. 